The academic, social, and vocational challenges faced by children with language impairment can be mitigated by early identification and provision of services. However, for the growing population of bilingual children who speak a language other than English at home, misidentification is a frequent problem. Accurate assessment can be complicated by limited English proficiency, low socioeconomic status, distributed linguistic knowledge across languages, and our limited understanding of phenomena unique to bilingual language use. Effective bilingual communication requires language control, the ability to choose the appropriate language based on the situation. Difficulties with language control may reflect an impaired bilingual system, but it remains unclear how language control abilities differ in bilingual children with and without impairment, and the contribution of factors other than language ability to the development of language control is not well understood. Adult models of language control focus on executive functions (higher-level cognitive control mechanisms), but these models have not been extended to children in more naturalistic discourse contexts. The goal of the proposed project is to examine language control in bilingual children with and without language impairment within a theoretical framework that considers the contributions of both language ability and executive functions. The project will include 70 bilingual children, ages 4-6, who speak English and Spanish. Participants will represent a full spectrum of language ability, including those with low skills in both languages who would qualify for a diagnosis of language impairment, those with low proficiency in only one language (i.e., English language learners and children experiencing attrition in Spanish), and those with typical abilities in both languages. Specific Aim 1 will employ an interactive picture description task to examine children's language control abilities at the discourse level in single-language and mixed-language contexts (Study 1). Specific Aim 2 will examine the extent to which language control relies on language ability. Language ability will be measured as both a continuous and a group variable, given the theoretical debate as to whether children with language impairment represent the low end of a continuum or a discrete category and given the practical difficulty of accurately identifying language impairment in bilingual children. Study 2 will assess language ability as a continuous predictor of language control. Study 3 will take a categorical approach by comparing the language control abilities of children at risk for language impairment and children with typical language. Specific Aim 3 will examine the contribution of executive functions to language control. Shifting skills, as measured by the Dimensional Change Card Sorting task in Study 4, will be considered alongside language ability as a predictor of language control. The proposed project thus tests an integrated model of linguistic and cognitive components of language control in bilingual children. Clinically, the findings will shed light on differences in language control between children with low and typical language skills and on whether such differences may assist in the assessment process.